Clock circuits for components such as, for example, integrated circuits are conventionally produced by mechanical or electrical counters. For example, clock circuits could use a quartz crystal because of its piezoelectric properties.
Conventional clock circuits, however, have a number of major drawbacks. For example, conventional clock circuits require a permanent source of power. If the power supply for the circuit is cut off, time can no longer be measured. The consumption of electrical power by such circuits is therefore relatively large. This problem becomes acute when a clock for smart cards has to be produced where consumption of electrical power is a constant concern.
Conventional clock circuits require a considerable footprint and thus could be detrimental in keeping an integrated circuit as compact as possible. Moreover, conventional clock circuits have a relatively complex structure and often times have a high manufacturing cost. Thus, conventional clock circuits cannot be used in integrated circuits where cost may be a factor.
Integrated circuit manufacturers are thus forced to compromise between the space required for mounting conventional clock circuits, the production cost of such circuits and the consumption of electrical power, which must remain relatively low.
There is therefore a need for an improved clock circuit for use in integrated circuits.